known as the white house correspondents' dinner. obama and d.c. heavyweights rubbing elbows with reporters and a-list hollywood celebrities. as customary, the president took the mike and made a series of jokes. how did he do? abc's reena ninan is in washington. >> reporter: that's right. a series of jokes that poked fun at him, republicans and even conan o'brien. overnight, washington insiders and hollywood stars came together for the yearly bash, a star-studded bashing of politics and the media, all in good fun. >> democrats, republicans, the white house, congress, you all came together to make this spoof. that's what real bipartisanship looks like. >> reporter: even kevin spacey's scheming congressman from netflix's "house of cards" was on hand. >> mr. president, welcome to nerd prom. >> reporter: for many, the highlight of the annaul event is the roast of the president. conducted this year by conan o'brien. >> your hair is so white, it could be a member of your cabinet. >> reporter: but president obama knew exactly how to roll with it. >> when